The present invention relates to refractory plastics. These are moldable materials that can be taken from containers and rammed into cracks and forms which then set upon heating. Presently such plastics are used in numerous furnaces ranging from steel making vessels to those used for carbon baking, aluminum, cement and the like. Conventionally such plastics use a combination of clay or bentonite and water as a plasticizing agent and phosphoric acid, a dextrin or molasses based material to obtain a set of the refractory. Some plastics also contain a water soluble resin as a setting agent.
A major problem with such plastics is that associated with the presence of water. Water prevents the satisfactory use of the hydratable refractory aggregates such as magnesite and reduces the effectiveness of carbon containing plastics due to oxidation. Another problem with such plastics is that the typical plasticizers such as ball clay or bentonite tend to flux the system at high temperatures.
In addition to refractory plastics, ramming mixes are also used to be rammed into cracks or forms in such furnaces. Typically these mixes are free flowing granular materials with enough tack to knit together when compacted into place into the cracks. The typical bonding phases are similar to refractory plastics, although several others including nonaqueous systems are also used. One bonding system for example is a liquid novolak or resol resin. These are commonly used for magnesite ramming mixes and alumina-carbon ramming mixes such as those used for blast furnace troughs. As has been noted above, water is not suitable when using a hydratable refractory aggregate such as magnesite. Though the bonding phases are similar, ramming mixes tend to differ from plastics mostly in moisture content. Increasing the moisture content of a typical ramming mix will usually result in a plastic body with reasonable properties. Increasing however the liquid resin content of a resin bonded ramming mix does not result in plastic cohesive body that has reasonable refractory properties.
Thus, no nonaqueous resin bonded plastics are commercially available with the exception of few mixes high in ball clay or other plasticizers. It has not been possible heretofore to have anhydrous monolithic refractory plastics which can use any type of refractory aggregate, including those that are generally hydratable, which are cohesive and which can be bonded with bond contents low enough to not adversely affect the desired physical properties of the refractory material.